This invention relates to jet aircraft engines and, more particularly, to self-contained apparatus mounted directly on the engine for raising and lowering the engine cowl sections to allow access to the workings of the engine by maintenance personnel.
In commercial aircraft having jet engines, it is oftentimes necessary to perform maintenance and repair work on the engine during stopovers along the flight route of the aircraft. Most jet engine cowlings are constructed as two bifurcated half cylinders hingedly attached to the engine or mounting strut so that they can be pivoted upwardly away from the engine core to permit maintenance personnel to access the engine core. Present devices used for opening the cowl halves or "D-ducts," as they are known in the industry, are either mechanical screw devices which have poor reliability or hydraulic actuators which are operated with a separate hand pump. In most cases in which the hand pump is used, one of the pumps is stowed on the aircraft so that it is available for use if necessary when the aircraft is on the ground. Since the pump is a separate article from the actuator, it is never certain that the ground station at which the plane is stopping en route has a pump available for use by the aircraft. In the hand pump system the hydraulic fluid for the actuator is contained within the pump itself and then pumped into the actuator during operation of the pump. After maintenance is performed and the cowl D-duct is closed, the hydraulic fluid is removed from the actuator and stored in the hand pump. The oil capacity of the hand pump limits the number of engine doors which can be opened at any given time and on multiengine aircraft it is seldom possible to have all the engines exposed for maintenance simultaneously. Also, there is practically no backup means available to open the cowl doors in case of failure of the hand pump or loss of the pump by ground personnel or misplacement of the hand pump aboard the aircraft.
It is therefore an object of the present invention to provide an apparatus for opening and closing the engine cowl halves covering the engines on a jet airplane that is self-contained and easily mountable on or adjacent the engine.
It is a further object to provide such an opening and closing apparatus which is relatively light and compact and which can open the cowl without regard to the condition of the remaining cowls on the other aircraft engines.
It is another object of this invention to provide such a self-contained opening and closing apparatus which has a high mechanical reliability and which is power-driven to permit easy opening of the heavy cowl doors and which has a backup source of manual drive in the event of failure of the power drive unit or power supply.